This application claims the priority benefit of Taiwan application serial No. 92134973, filed on Dec. 11, 2003.
1. Field of the Invention
The present invention relates to a chemical mechanical polishing (CMP) apparatus, and more particularly to a chemical mechanical polishing (CMP) apparatus, a profile control system and a conditioning method thereof.
2. Description of the Related Art
During semiconductor manufacturing, the planarization of wafers are more and more important because it will affect the subsequent photolithographic processes. Usually, the planarization of wafers is performed by CMP because of its low selective polishing characteristic. It can be applied to the shallow trench isolation process in the front-end processing, the multi-layer interconnect process in the back-end processing, advance device manufacturing processes, planarization of micro-machines and panel displays.
Traditionally, the CMP process comprises an in-line polishing step and a pad conditioning step thereafter. The conditioning step serves conditioning the profile of the polishing pad by the conditioner over the polishing pad. Moreover, the conditioning recipe is fixed.
When the uniformity of the wafers becomes worse during the production, the polishing pad is not the first priority to be checked. However, the profile of the polishing pad substantially affects the planarization of the wafers and the tool performances. If the profile of the polishing pad is not properly maintained, the service life of the polishing pad is going to be reduced.
Therefore, an object of the present invention is to provide a profile control system of a polishing pad, adapted to control the profile of the polishing pad for reducing the variation of the uniformity of wafers.
Another object of the present invention is to provide a chemical mechanical polishing apparatus, adapted to reduce the variation of the uniformity of wafers for obtaining a desired profile of the polishing pad after the chemical mechanical polishing process.
The other object of the present invention is to provide a chemical mechanical polishing apparatus, adapted to polish a plurality of wafers simultaneously and to control the profiles of the polishing pads.
A further object of the present invention is to provide a method of controlling the profile of the polishing pad, adapted to adjust the processing recipe of a conditioner for controlling the profile of the polishing pad.
According to the objects above, the present invention discloses a profile control system of a polishing pad, adapted for a chemical mechanical polishing apparatus. The chemical mechanical polishing apparatus comprises a polishing pad, a polishing table, a polishing head and a conditioner, wherein the polish pad comprises a transparent region. The profile control system of a polishing pad comprises: at least one illuminant, a detector and a processor. The illuminant is configured in the polishing table, wherein the illuminant corresponds to the transparent region of the polishing pad. The detector is configured over the polishing pad for detecting the light through the transparent region of the polishing pad. According to a detection of the detector, a processor evaluates a thickness and a profile of the polishing pad and transmits a processing signal to the conditioner for adjusting a processing recipe of the conditioner to obtain a desired profile of the polishing pad.
The present invention also discloses a chemical mechanical polishing apparatus, adapted to polish a wafer. The chemical polishing apparatus comprises a polishing table, a polishing pad, a detector, a processor, a conditioner and a polishing head. The polishing table has at least one illuminant. The polishing pad covers the polishing table, wherein the polishing pad has at least one transparent region corresponding to the illuminant of the polishing table. The detector is configured over the polishing pad for detecting a light passing through the transparent region of the polishing pad. The processor is coupled to the detector, wherein the processor is adapted to evaluate a thickness and a profile of the polishing pad and transmit a processing signal according to the thickness and the profile determined by the processor. The conditioner is configured over the polishing pad and coupled to the processor, wherein the conditioner is adapted to adjust a processing recipe according to the processing signal from the processor to obtain a desired profile of the polishing pad. The polishing head is configured over the polishing pad and beside the conditioner for holding the wafer.
The present invention also discloses a chemical mechanical polishing apparatus, adapted to polish a plurality of wafers. The chemical mechanical polishing apparatus comprises a plurality of polishing tables, a plurality of polishing pads, a plurality of detectors, a processor, conditioners and a plurality of polishing heads. Each of the polishing tables has at least one illuminant. The plurality of polishing pads is positioned over the corresponding polishing tables, wherein each of the polishing pads has at least one transparent region corresponding to the each illuminant of the polishing tables. The plurality of detectors is configured over the polishing pad for detecting a light through the transparent regions of the polishing pads. The processor is coupled to the detectors, wherein the processor is adapted to evaluate the thickness and profile of the polishing pads and transmits a plurality of processing signals according to the thickness and profiles determined by the processors. The conditioners are configured over the polishing pads and coupled to the processor, wherein the conditioners are adapted to adjust processing recipes according to the processing signals from the processor to maintain desired profiles of the polishing pads. The polishing heads are configured over the polishing heads and beside the conditioners for holding the wafers.
The present invention further discloses a method of controlling polishing pad profile, adapted to adjust a processing recipe of a conditioner for controlling a profile of a polishing pad. The method comprises: using a detector for detecting a light from a polishing table under the polishing pad; using a processor coupled to the detector for determining a thickness of the polishing pad and transmitting a processing signal according to the thickness of the polishing pad determined by the processor; and adjusting the processing recipe of the conditioner according to the processing signal from the processor, for obtaining a desired profile of the polishing pad.
The chemical mechanical polishing apparatus of the present invention uses a profile control system in conjunction with the transparent region of the polishing pad and the illuminant in the polishing table for controlling the profile of the polishing pad so as to reduce the variation of the uniformity of the wafers and to obtain a desired profile of the polishing pad. Therefore, when the profile of the polishing pad is determined to be out of spec, the system conditioning process is activated for conditioning the polishing pad until a desired profile is obtained. Moreover, the present invention can be applied to an in-situ or an ex-situ process. The in-situ process continuously increases or reduces the dressing amount according to the processing data during the process. The ex-situ process increases or reduces the dressing amount according to the stored processing data.
In order to make the aforementioned and other objects, features and advantages of the present invention understandable, a preferred embodiment accompanied with figures is described in detail below.